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Ben-Tov D, Mafessoni F, Cucuy A, Honig A, Melamed-Bessudo C, Levy AA. Uncovering the dynamics of precise repair at CRISPR/Cas9-induced double-strand breaks. Nat Commun 2024; 15:5096. [PMID: 38877047 PMCID: PMC11178868 DOI: 10.1038/s41467-024-49410-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 06/05/2024] [Indexed: 06/16/2024] Open
Abstract
CRISPR/Cas9 is widely used for precise mutagenesis through targeted DNA double-strand breaks (DSBs) induction followed by error-prone repair. A better understanding of this process requires measuring the rates of cutting, error-prone, and precise repair, which have remained elusive so far. Here, we present a molecular and computational toolkit for multiplexed quantification of DSB intermediates and repair products by single-molecule sequencing. Using this approach, we characterize the dynamics of DSB induction, processing and repair at endogenous loci along a 72 h time-course in tomato protoplasts. Combining this data with kinetic modeling reveals that indel accumulation is determined by the combined effect of the rates of DSB induction processing of broken ends, and precise versus error repair. In this study, 64-88% of the molecules were cleaved in the three targets analyzed, while indels ranged between 15-41%. Precise repair accounts for most of the gap between cleavage and error repair, representing up to 70% of all repair events. Altogether, this system exposes flux in the DSB repair process, decoupling induction and repair dynamics, and suggesting an essential role of high-fidelity repair in limiting the efficiency of CRISPR-mediated mutagenesis.
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Affiliation(s)
- Daniela Ben-Tov
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Fabrizio Mafessoni
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Amit Cucuy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Arik Honig
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Cathy Melamed-Bessudo
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
| | - Avraham A Levy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
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Yenerall P, Zhou L. Identifying the mechanisms of intron gain: progress and trends. Biol Direct 2012; 7:29. [PMID: 22963364 PMCID: PMC3443670 DOI: 10.1186/1745-6150-7-29] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/22/2012] [Indexed: 12/22/2022] Open
Abstract
Abstract Continued improvements in Next-Generation DNA/RNA sequencing coupled with advances in gene annotation have provided researchers access to a plethora of annotated genomes. Subsequent analyses of orthologous gene structures have identified numerous intron gain and loss events that have occurred both recently and in the very distant past. This research has afforded exceptional insight into the temporal and lineage-specific rates of intron gain and loss among various species throughout evolution. Numerous studies have also attempted to identify the molecular mechanisms of intron gain and loss. However, even after considerable effort, very little is known about these processes. In particular, the mechanism(s) of intron gain have proven exceptionally enigmatic and remain topics of considerable debate. Currently, there exists no definitive consensus as to what mechanism(s) may generate introns. Because many introns are known to affect gene expression, it is necessary to understand the molecular process(es) by which introns may be gained. Here we review the seven most commonly purported mechanisms of intron gain and, when possible, summarize molecular evidence for or against the occurrence of each of these mechanisms. Furthermore, we catalogue indirect evidence that supports the occurrence of each mechanism. Finally, because these proposed mechanisms fail to explain the mechanistic origin of many recently gained introns, we also look at trends that may aid researchers in identifying other potential mechanism(s) of intron gain. Reviewers This article was reviewed by Eugene Koonin, Scott Roy (nominated by W. Ford Doolittle), and John Logsdon.
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Affiliation(s)
- Paul Yenerall
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Golubov A, Yao Y, Maheshwari P, Bilichak A, Boyko A, Belzile F, Kovalchuk I. Microsatellite instability in Arabidopsis increases with plant development. PLANT PHYSIOLOGY 2010; 154:1415-27. [PMID: 20817752 PMCID: PMC2971617 DOI: 10.1104/pp.110.162933] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 08/24/2010] [Indexed: 05/23/2023]
Abstract
Plant development consists of the initial phase of intensive cell division followed by continuous genome endoreduplication, cell growth, and elongation. The maintenance of genome stability under these conditions is the main task performed by DNA repair and genome surveillance mechanisms. Our previous work showed that the rate of homologous recombination repair in older plants decreases. We hypothesized that this age-dependent decrease in the recombination rate is paralleled with other changes in DNA repair capacity. Here, we analyzed microsatellite stability using transgenic Arabidopsis (Arabidopsis thaliana) plants that carry the nonfunctional β-glucuronidase gene disrupted by microsatellite repeats. We found that microsatellite instability increased dramatically with plant age. We analyzed the contribution of various mechanisms to microsatellite instability, including replication errors and mistakes of DNA repair mechanisms such as mismatch repair, excision repair, and strand break repair. Analysis of total DNA polymerase activity using partially purified protein extracts showed an age-dependent decrease in activity and an increase in fidelity. Analysis of the steady-state RNA level of DNA replicative polymerases α, δ, Pol I-like A, and Pol I-like B and the expression of mutS homolog 2 (Msh2) and Msh6 showed an age-dependent decrease. An in vitro repair assay showed lower efficiency of nonhomologous end joining in older plants, paralleled by an increase in Ku70 gene expression. Thus, we assume that the more frequent involvement of nonhomologous end joining in strand break repair and the less efficient end-joining repair together with lower levels of mismatch repair activities may be the main contributors to the observed age-dependent increase in microsatellite instability.
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Contrasting evolutionary dynamics between angiosperm and mammalian genomes. Trends Ecol Evol 2009; 24:572-82. [PMID: 19665255 DOI: 10.1016/j.tree.2009.04.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 04/06/2009] [Accepted: 04/22/2009] [Indexed: 12/23/2022]
Abstract
Continuing advances in genomics are revealing substantial differences between genomes of major eukaryotic lineages. Because most data (in terms of depth and phylogenetic breadth) are available for angiosperms and mammals, we explore differences between these groups and show that angiosperms have less highly compartmentalized and more diverse genomes than mammals. In considering the causes of these differences, four mechanisms are highlighted: polyploidy, recombination, retrotransposition and genome silencing, which have different modes and time scales of activity. Angiosperm genomes are evolutionarily more dynamic and labile, whereas mammalian genomes are more stable at both the sequence and chromosome level. We suggest that fundamentally different life strategies and development feedback on the genome exist, influencing dynamics and evolutionary trajectories at all levels from the gene to the genome.
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Boyko A, Zemp F, Filkowski J, Kovalchuk I. Double-strand break repair in plants is developmentally regulated. PLANT PHYSIOLOGY 2006; 141:488-97. [PMID: 16474027 PMCID: PMC1475443 DOI: 10.1104/pp.105.074658] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In this study, we analyzed double-strand break (DSB) repair in Arabidopsis (Arabidopsis thaliana) at various developmental stages. To analyze DSB repair, we used a homologous recombination (HR) and point mutation reversion assays based on nonfunctional beta-glucuronidase reporter genes. Activation of the reporter gene through HR or point mutation reversion resulted in the appearance of blue sectors after histochemical staining. Scoring of these sectors at 3-d intervals from 2 to 31 d post germination (dpg) revealed that, although there was a 100-fold increase in the number of genomes per plant, the recombination frequency only increased 30-fold. This translates to a recombination rate at 31 dpg (2.77 x 10(-8)) being only 30% of the recombination rate at 2 dpg (9.14 x 10(-8)). Conversely, the mutation frequency increased nearly 180-fold, resulting in a 1.8-fold increase in mutation rate from 2 to 31 dpg. Additional analysis of DSBs over the early developmental stages revealed a substantial increase in the number of strand breaks per unit of DNA. Furthermore, RNA analysis of Ku70 and Rad51, two key enzymes in two different DSB repair pathways, and further protein analysis of Ku70 revealed an increase in Ku70 levels and a decrease of Rad51 levels in the developing plants. These data suggest that DSB repair mechanisms are developmentally regulated in Arabidopsis, whereby the proportion of breaks repaired via HR substantially decreases as the plants mature.
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Affiliation(s)
- Alexander Boyko
- Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
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Affiliation(s)
- Seisuke Kimura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda-shi, Chiba, Japan
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Yokota Y, Shikazono N, Tanaka A, Hase Y, Funayama T, Wada S, Inoue M. Comparative radiation tolerance based on the induction of DNA double-strand breaks in tobacco BY-2 cells and CHO-K1 cells irradiated with gamma rays. Radiat Res 2005; 163:520-5. [PMID: 15850413 DOI: 10.1667/rr3355] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Higher plants are generally more tolerant to ionizing radiation than mammals. To explore the radiation tolerance of higher plants, the induction of DNA double-strand breaks (DSBs) by gamma rays was investigated in tobacco BY-2 cells and compared with that in Chinese hamster ovary (CHO)-K1 cells as a reference. This is the first examination of radiation-induced DSBs in a higher plant cell. The resulting DNA fragments were separated by pulsed-field gel electrophoresis and stained with SYBR Green I. The initial yield of DSBs was then quantified from the fraction of DNA fragments shorter than 1.6 Mbp based on the assumption of random distribution of DSBs. The DSB yield in tobacco BY-2 cells (2.0 +/- 0.1 DSBs Gbp(-1) Gy(-1)) was only one-third of that in CHO-K1 cells. Furthermore, the calculated number of DSBs per diploid cell irradiated with gamma rays at the mean lethal dose was five times greater in BY-2 cells (263 +/- 13) than in CHO-K1 cells. These results suggest that the radiation tolerance of BY-2 cells appears to be due not only to a lower induction of DNA damage but also to a more efficient repair of the induced DNA damage.
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Affiliation(s)
- Yuichiro Yokota
- Faculty of Agriculture, Kyoto Prefectural University, Kyoto 606-8522, Japan.
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Pelczar P, Kalck V, Gomez D, Hohn B. Agrobacterium proteins VirD2 and VirE2 mediate precise integration of synthetic T-DNA complexes in mammalian cells. EMBO Rep 2004; 5:632-7. [PMID: 15153934 PMCID: PMC1299075 DOI: 10.1038/sj.embor.7400165] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 03/04/2004] [Accepted: 03/31/2004] [Indexed: 11/09/2022] Open
Abstract
Agrobacterium tumefaciens-mediated plant transformation, a unique example of interkingdom gene transfer, has been widely adopted for the generation of transgenic plants. In vitro synthesized transferred DNA (T-DNA) complexes comprising single-stranded DNA and Agrobacterium virulence proteins VirD2 and VirE2, essential for plant transformation, were used to stably transfect HeLa cells. Both proteins positively influenced efficiency and precision of transgene integration by increasing overall transformation rates and by promoting full-length single-copy integration events. These findings demonstrate that the virulence proteins are sufficient for the integration of a T-DNA into a eukaryotic genome in the absence of other bacterial or plant factors. Synthetic T-DNA complexes are therefore unique protein:DNA delivery vectors with potential applications in the field of mammalian transgenesis.
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Affiliation(s)
- Pawel Pelczar
- Friedrich Miescher-Institut for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
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Ilnytskyy Y, Boyko A, Kovalchuk I. Luciferase-based transgenic recombination assay is more sensitive than beta-glucoronidase-based. Mutat Res 2004; 559:189-97. [PMID: 15066586 DOI: 10.1016/j.mrgentox.2004.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 01/30/2004] [Accepted: 02/05/2004] [Indexed: 01/05/2023]
Abstract
Study of the DNA repair and genome stability in plants is directly dependent on the availability of an easy, inexpensive, and reliable assay. Marker gene-based homologous recombination (HR) assays were introduced more than a decade ago and have been intensively used ever since. Here, we compared several transgenic Arabidopsis and tobacco lines that carried in their genome the luciferase (LUC) or the beta-glucoronidase (uidA or GUS) substrates for HR. The average recombination frequency detected with the luciferase transgene was nearly 9.0-fold higher in Arabidopsis and 12.4-fold higher in tobacco plants. Importantly, both transgenes were under the control of 35S promoter and had similar expression levels throughout the plants. Irradiation with UVC increased the HR frequency similarly in both transgenes. The actual difference in the frequency of HR in Arabidopsis and tobacco possibly results from differing sensitivity to detection of transgene activity. Thus, we could suggest that luciferase recombination assay, due to its higher sensitivity, should be the assay of choice when plant genome stability is studied.
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Affiliation(s)
- Yaroslav Ilnytskyy
- Department of Biological Sciences, University of Lethbridge, 4401 University Drive, Lethbridge, Alta., Canada T1K 3M4
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